General Greenhouse IPM

Insects and diseases are a major challenge to greenhouse production. IPM is an important tool in the management of these pests. The primary goal of IPM is to optimize pest control in an economically and ecologically sound way. IPM involves the integration of cultural, physical, biological, and chemical practices to grow crops with minimal use of pesticides. Monitoring, sampling, and record keeping are used to determine when control options are needed to keep pests below an economically damaging threshold. Pest management, not eradication, is the goal of IPM.

A Guide to Insects and Related Pests of Floricultural Crops in New England: For Commercial Growers (1), a University of Massachusetts Cooperative Extension System publication, outlines the basic strategy on greenhouse IPM:

IPM is a simple, practical, and, most important, flexible way to manage insects, mites, diseases, weeds and vertebrates.

Integrated pest management is adaptable to all greenhouse-grown crops and involves specific techniques to manage pests. These techniques are:

Monitoring or scouting program

inidual plant inspection

yellow, blue, and hot pink sticky cards

indicator plants

Pest identification and life stages

Record keeping to identify trends and direction for your pest management program

Exclusion techniques to prevent pests from entering the production area

Insect screens to exclude aphids, whiteflies, and thrips from entering through doors and ventilating systems

Cultural practices to prevent problems

soil testing

sanitation

Biological controls, living organisms used to reduce the incidence of pest organisms

Insect growth regulators, insecticides that interfere with normal insect development or the molting process

Chemical controls

proper choice of pesticides

proper timing of pesticide application

proper application procedure

It is important to understand the life cycle and behavior of insect pests in order to develop an effective control strategy. Knowledge about the weak link in a pest's life cycle can help growers choose the most appropriate control strategy.

There are several practices that will increase the success of an IPM program (2):

A selection of the better publications on greenhouse IPM is listed in the Resources section below. The publications from Applied Bio-Nomics, The Green Spot, and California Environmental Protection Agency are essential references that every IPM grower should have on his or her bookshelf.

Crop Scouting and Trapping

To detect early infestations, a crop scouting program that includes both sticky trap cards (usually yellow) and visual inspection is critical. Scouting should be done once a week, and more often after an infestation is detected. Regular scouting is also necessary to monitor the efficacy of control measures. A hand lens is a useful tool to detect live pests as well as signs of pest activity—e.g., frass (feces), cast skins, honeydew, etc.

Monitoring records can be kept on paper or in a computer. (Computers are usually better for producing graphs, which show trends more easily.) State and federal regulations will soon require that all greenhouses that apply pesticides keep records on what was applied. If plant injury symptoms appear, the grower can see quickly what chemicals or biocontrols have been used, and how the environment affected the crop. (3) And, thorough records are invaluable in negotiations with suppliers for compensation for problems traced to receipt of diseased stock. (3)

At a minimum, records should include:

Minimum and maximum temperatures for each day

Counts from sticky cards, changed weekly

Counts of pests on the plants, including stage of growth (egg, immature, adult)

Plant growth and development based on measurements of selected, flagged plants

Sticky ribbons are long sticky insect strips that are hung throughout the greenhouse as a means of reducing insect populations of whiteflies, leafminers, aphids, fungus gnats, and thrips. Unlike sticky traps that are used for monitoring, the primary purpose of sticky ribbons is to reduce the numbers of flying insect pests by simply catching them.

Sanitation

Sanitation is key for controlling pests in greenhouses. The goal of sanitation is to eliminate all possible sources of the pest. Weeds inside and near the outside of the greenhouse can harbor pests. It's best to pull the weeds inside the greenhouse rather than spray them, since insects may survive the spray and migrate onto crops. Bag all weeds and dispose of them outside the greenhouse.

In addition, a 10-30 foot vegetation-free zone around the outside perimeter of the greenhouse—especially near vents and opening—can provide a dramatic decrease in pests. A heavy-duty geotextile weed barrier (e.g., DeWitt Sunbelt® Weed Barrier) covered with bark mulch or gravel can provide a pleasant vegetation-free zone, and eliminate the need for herbicides.

Plant debris from previous crops can also be a source of both immature and adult pests. Clean up all debris from previous crops and dispose of infested plants, or any infested growth. Ideally, the greenhouse should be thoroughly cleaned and left empty for one week prior to beginning the next crop. This enables removal of all pest stages, and starves any remaining adults. Closing up the greenhouse when it is empty in summer will increase the temperature and help eradicate pests.

Inside the greenhouse, a clean stock program should be in place. This includes temporary quarantine and inspection of all plants upon arrival from other greenhouses, and regular monitoring of stock plants used for propagation. If a separate section of the greenhouse can't be dedicated to this purpose, flag all incoming plants. All new plant material should be thoroughly inspected (with a 10X hand lens) for the presence of pests to ensure that no infested plants are introduced into the greenhouse. Workers in the greenhouse should avoid wearing yellow clothing, since many pests are attracted to this color and may hitch a ride on the fabric from one greenhouse to the next.

Screening

Insect screens physically exclude the entry of lightweight, airborne insects like aphids, whiteflies, and thrips from the greenhouse through doors, cooling pads, and ventilation units. Although the tiny pores of insect screens prevent entry of insects, they can also impede the flow of air. Some specialists say the area the screen covers should be three times that of the area covered (doors, ventilation) to facilitate sufficient air intake. To accomplish this, screen houses designed to enclose both the cooling pads and greenhouse entranceway can be installed.

Biological Control

Biological control is the use of living organisms to control crop pests. Biological control of greenhouse insect pests can be achieved through release of biocontrol agents like predatory mites, pirate bugs, soil-dwelling mites, and parasitic insects.

Implementing a biological control program in a greenhouse is management intensive and requires more knowledge on the part of the grower than do traditional pest control programs. Proper species identification is very important before a control program using predators or parasites is initiated. Release rate, timing, placement, temperature, and pesticide use also influence the success or failure of biological control efforts. Rigorous monitoring is necessary for proper timing of biocontrol agent releases, as is a reliable supply of the natural enemies.

Knowing the lifespan of the beneficials selected is important too, since fewer releases are required if sufficient numbers of parasites or predators are maintained. Some species of beneficials live only a few days and therefore must be released biweekly. Other species live for several weeks; consequently, they are released less frequently.

The level of control provided by a natural enemy will also vary with crop species. It is therefore more difficult for bedding and other container-plant growers to implement biocontrol, since they produce a wide variety of crops.

One of the most important things to keep in mind when using biologicals is that even residual insecticide can harm them. This happened to a grower who tried to use Encarsia formosa, a parasitic wasp, on his poinsettias. (4) The previous crop had been sprayed with a pesticide two months before applying the wasps, but all the wasps were killed by the residual.

Biologicals also allow more thorough coverage than spraying and a more efficient use of labor, since workers don't have to wait for re-entry into the greenhouse. (4)

Generally, the best time to release beneficials is at the first sign of a pest infestation. Early morning and dusk are the optimum release times.

Suppliers of biocontrol agents can provide technical assistance and help growers get started in a biocontrol program. When requesting assistance or ordering beneficials from a supplier, the grower should be able to provide information such as: what the pest is, how much square footage is affected, crop rotations, fertility programs, and pesticides that have been used in the greenhouse.

The Canadian greenhouse vegetable industry—which is about four times the size of the U.S. industry—is largely based on biological controls. In 1995, tomato growers in British Columbia spent 50 cents per square meter per season on biological control, primarily on the parasitic wasp Encarsia formosa. (5)

There are several items to keep in mind when using biological controls (6):

No single pest control method is 100% effective.

This method often involves more work at first than chemical control, and it may require changes in production methods.

Biologicals are often highly susceptible to pesticides. When choosing pesticides, select those with the shortest residual life and the highest specificity.

Since many biologicals work slowly, they are best used when pest numbers are fairly low.

Most predators and parasites perform best at moderate temperatures (65-85°F) and humidities (60-90%).

If the greenhouse is allowed a dormant period (either very hot or very cold), the beneficials will die.

If the pest level is very high when beneficials are first introduced, they probably will not provide enough control.

The effectiveness of the same beneficial may be different on different plants. For instance, beneficials are often less effective on hairy-leaved plants like tomatoes.

Insect Growth Regulators

Insect growth regulators (IGRs) are another least-toxic pesticide control option for pests. IGRs typically kill insects by disrupting their development. They have a complex mode of action that precludes insects from rapidly developing resistance. IGRs can work in one of several ways: 1) they can mimic juvenile hormones, so that insects never enter the reproductive stage of development; 2) they can interfere with the production of chitin, which makes up the shell of most insects; or 3) they can interfere with the molting process.

IGRs usually work through ingestion, so good spray coverage is essential. They generally don't affect non-target species—such as humans, birds, fish or other vertebrates. For most IGRs there are minimal re-entry restrictions. IGRs typically take several days to have an effect on pest populations. Because IGRs do not affect mature insects, adult beneficials released into the greenhouse after an IGR application are not likely to be affected. Use of IGRs is generally prohibited by organic certification organizations because the products are synthetic.

IGRs can sometimes be used in conjunction with biological control efforts and may provide growers with a "safety net" should beneficials fail to keep the pests below economically damaging levels. Table 1 lists some well-known insect growth regulators. (See the Resources section for suppliers)

Biorational Pesticides

The integration of biorational pesticides (also known as least-toxic or biopesticides) in greenhouses is often necessary in addition to cultural and biological control measures. When the use of a pesticide is necessary, materials should be selected that are least harmful to the predators and parasites released into the greenhouse. Insecticidal soap, horticultural oils, and the bacterium Bacillus thuringiensis are examples of insecticides that can be safely integrated into a biological control program. The advantages of biopesticides over conventional chemicals are their selectivity to a targeted pest, lower toxicity to beneficial insects and greenhouse workers, and shorter re-entry intervals (REI).

BotaniGard™ (from Mycotech) and Naturalis-O™ (from SePro) are the two commercial formulations of B. bassiana that are available for greenhouse use. B. bassiana is a naturally occurring fungus that attacks a wide range of pests—including aphids, whiteflies, thrips and spider mites. B. bassiana has been found to be compatible with predators such as Encarsia spp., Eretmocerus spp. and Chrysoperla spp.

Spinosad

Early in 1999, Conserve SC™ from Dow AgroSciences was registered for use on greenhouse ornamentals. The active ingredient comes from the soil-inhabiting actinomycete Saccharopolyspora spinosa. Conserve is effective against many different species of caterpillars, leafminers, and thrips. Experiments performed at the Ohio State University showed that Conserve provided excellent control of Western flower thrips. (7)

Hot Pepper Wax and Garlic Extract

These products are actually insect repellents. Hot Pepper Wax™ contains paraffin (refined wax) and capsaicin (the "hot" in hot peppers). Another study at Ohio State showed that Hot Pepper Wax did not control Western flower thrips, but was effective against two-spotted spider mite. (7) Products containing garlic also work to repel insects.

Greenhouse Disease Control

The greenhouse climate is ideal for the development of plant diseases. An integration of cultural practices, environmental control, biological control, and natural control products will be needed to prevent widespread outbreak.

Many fungicides are also toxic to beneficial organisms, and should be avoided if possible. Alternative disease control techniques include the use of disease resistant varieties, disease-free seeds and plants, well-drained soil, air circulation, weed eradication, humidity control, sanitation, disease-suppressive composts, compost watery extracts, and microbial antagonists.

Disease control may be classified into two approaches: 1) those aimed at the root environment, and 2) those aimed at the aerial environment.

The Root Environment

Soil disinfection (i.e., sterilization) is an important part of soil-borne disease control when raising vegetables by the ground culture method or when soil-based potting mixes are used. Soil-borne diseases include damping-off (Pythium and Rhizoctonia), black root rot (Thielaviopsis), and several other root rots and wilts caused by Fusarium and Phytophthera. Potting mixes based on compost, peat moss, vermiculite, perlite, and bark are typically pathogen-free and do not require prior sterilization.

Sterilization involves heating the soil to 212°F for 30 minutes, a process that kills most organisms in the soil. Chemical changes also occur in the soil and may affect plant nutrient uptake to the following crop. Pasteurization involves heating the soil to only 160°F for 30 minutes. While most harmful pathogens are killed at this temperature, many beneficial soil organisms survive. Thus, pasteurization is the preferred method in organic programs.

Electrical heat treatment, which is done inside a steel chamber surrounded by heating coils, is limited to treating about a cubic yard of soil at a time. Its primary use is in the pasteurization of small batches of sand and soil for potting mixes.

Accordingly, steam pasteurization and soil solarization are the two most viable options for sterilizing greenhouse soils or large volumes of soil-based mixes. Biological control is complementary to these two methods.

Steaming

Steam was the primary method of soil sterilization in the greenhouse industry prior to the emergence of soil fumigants. Steam heat is highly effective and environmentally safe. Equipment and fuel costs are expensive, however, and treatment between crops is labor and time consuming. These are the chief reasons many growers shifted to soilless mixes.

Soil solarization is the process of tarping moist soils with clear polyethylene to trap solar radiation and raise soil temperatures to levels lethal to most pathogens and weed seeds. Solarization is most effective when applied for at least 30 days in midsummer. Two layers of polyethylene, separated by fillers (i.e., pvc pipes or 2'x 4's) spaced every few feet to create an air space, increases the efficiency of solarization.

Solarization in greenhouses is a proven means of soil sterilization, and is practiced worldwide in Japan, Israel, Greece, France, Italy, Belgium, Portugal, and Spain (9-11), in addition to the United States and Canada.

Solarization can also be used to pasteurize sand or soil intended for potting media, or to treat used media. (12) A simple technique developed in Florida (13), is to fill a black plastic trash bag with media, which is then sealed in a transparent plastic bag. The double-wrapped media is placed in the open on asphalt or concrete and spread to a uniform depth of 3 inches.

As long as the trash bag received one full day of sunshine from April through August, the temperatures reached or exceeded 113°F for more than 2 hours. This temperature, which was monitored with a thermometer inserted into the media, was considered the minimum treatment period for plant-parasitic nematodes. This method yields about 24 liters of media.

Biological control of pathogens in greenhouse soils and potting mixes is accomplished through natural control via cultural practices, and secondly, through applied biocontrols. The introduction of biocontrol agents, or antagonists, is the next form of biological soil disinfection. Biological fungicides are a promising alternative to synthetic fungicides.

There are several new biocontrols available for suppressing root diseases. One product is RootShield™, a biofungicide that controls root diseases caused by Pythium, Rhizoctonia, Fusarium, and Sclerotinia. RootShield contains the fungus Trichoderma harzianum and is sold either as granules or a drench. SoilGard 12G™ is another biofungicide that controls Pythium, Fusarium, Rhizoctonia, Phytophthora and Thielaviopsis (when co-applied with sulfur). The active ingredient is the fungus Gliocladium virens. SoilGard is sold as granules that can be incorporated into the soil mix. Another product is MycoStop™, sold as a wettable powder. MycoStop contains the actinomycete Streptomyces griseoviridis and controls Fusarium, although it may control other root diseases. See Appendix III: Biorational Pesticides for further information.

Cultural practices that promote soil health include crop rotation and use of tilled-in crop residues and green manures or organic amendments brought in from off site.

The beneficial effect of crop rotation on plant health and yield is probably due to changes in soil microflora. These shifts result in increasing numbers of beneficial microorganisms (including nitrifying and other useful bacteria, antagonists of pathogens, etc.), and in decreasing numbers of noxious ones (pathogens and antagonists of beneficial microorganisms). (15)

In some greenhouses, a short-term break crop—such as annual ryegrass, oats, buckwheat, or rapeseed—may fit into the rotation and be used to increase organic matter. Another option is to rely on organic amendments or green leaf manures brought in from off site. Amendments such as fresh residues, composts, and manures result in soil improvement through a proliferation of microflora.

Green leaf manures are field-grown cover crops that are chopped and harvested green, then transported inside the greenhouse to be incorporated into the soil. Many studies have shown that crucifer residues from rapeseed and oilseed radish cover crops produce toxic gases that suppress soilborne pathogens. Additionally, soil solarization, following incorporation of cruciferous residues, increases the efficiency of soilborne pathogen control.

The role of composts as a slow-release nutrient source in organic production is well established. Recently, the role of composts as amendments for the control of soilborne plant pathogens has increased interest in similar use in conventional agriculture. Much of the pioneering research on this topic has been conducted by Dr. Harry Hoitink (16-18) at Ohio State University.

In container production, disease-suppressive composts are commercially available in both peat and soil-based media. Dr. Frank Regulski, who is President of BioComp, Inc., an Edenton, N.C., company that developed a series of disease-suppressive mixes, said that suppressive properties come from a certain composting technique that yields antibiotic (antagonistic) and competitive (saprophytic) responses. (19)

Natural disease-suppressive potting mixes—based on composts—are available through several commercial sources. These products may, however, contain starter fertilizers and wetting agents which would restrict their use in organic certification programs. Contact the manufacturers for clarification on these ingredients. Some companies will blend a special batch that excludes restricted ingredients, therefore making them suitable for organic production. For more information on these companies, ask for ATTRA's publication Disease Suppressive Potting Mixes. This publication also discusses how to inoculate potting mixes with mycorrhizae. Mycorrhizae colonize plant roots and protect them against certain pathogenic fungi, including various Pythium and Fusarium species. (20)

Greenhouse climates are warm, humid, and wind-free—an ideal environment for the development of many foliar and stem diseases. For the majority of pathogenic fungi and bacteria, infection usually occurs when a film or drop of water on the plant surface persists. Unless temperature, humidity, and ventilation are well regulated, this surface water can remain in the greenhouse until infection becomes assured. (21)

Agricultural engineers at the Ohio Agricultural Research and Development Center (OARDC) in Wooster, Ohio, are knowledgeable about computer environment controlled greenhouses and should be able to direct you to appropriate systems. Contact:

Greenhouse growers have fewer alternative control products for diseases than for insects. Copper- and sulfur-based fungicides are the only commercial fungicides acceptable in certified organic programs. Coppers exhibit both fungicidal and bacterial control properties. Sulfurs are noted for control of mildews. Alternative disease control strategies, although based more on grower's experience and limited research, include compost watery extracts (see ATTRA's publication Compost Teas for Plant Disease Control for more information), biodynamic herbal extracts (see ATTRA's publication Biodynamic Farming and Compost Preparation) and foliar feeding below.

Biofungicides for foliar disease control are also available. AQ10™ contains the fungus Ampelomyces quisqualis and controls powdery mildew. Trichodex™ controls botrytis. TopShield™ contains Trichoderma harzianum and controls botrytis and powdery mildew. TopShield should become commercially available in 1999. See Appendix III: Biorational Pesticides for further information.

Foliar Feeding

Foliar feeding is used by many organic growers to induce resistance to foliar disease. Seaweed and fish emulsion are the two products most commonly applied. More sophisticated foliar programs are being formulated in conjunction with refractometers and radionics instruments. Although the mechanism for resistance is not clear, modification of the leaf surface and enhanced plant nutrition is suspected. It has been stated that foliar fertilization indirectly protects against plant pathogens by increasing natural plant immunity through improvement of the plant's nutritional status. (22)

Evidence is also strong that foliar feeding can have a dramatic effect on the rhizosphere microflora via changes in root exudates. (15) Such changes in root exudates may lead to an increase of antagonists and thus enhance biological control of pathogens in the root environment as well. (15) Further information on foliar feeding is available from ATTRA on request.

Baking Soda

Baking soda has for many years been used in Europe as a mild fungicide by rose growers and organic gardeners. Recently, plant pathologists at Cornell University confirmed through research that baking soda exhibits fungicidal activity against powdery mildew and several other diseases on ornamentals. (23) They determined that a mixture of 0.5% baking soda (about 5 level teaspoons per gallon of water) and 0.5% horticultural oil showed the greatest activity.

A new product containing baking soda, called Remedy™, is now available for use as a pesticide. Remedy is effective against black spot, powdery mildew, leaf spots, anthracnose, phoma, phytophthora, scab, and botrytis. Remedy should be applied at the first sign of disease and repeated at one- or two-week intervals until the problem subsides. A six-ounce bottle (enough to make 12 gallons of spray) is available for $15 from:

References

Gentile, A.G., and D.T. Scanlon; Revised by Tina Smith. 1992. A Guide to Insects and Related Pests of Floricultural Crops in New England: For Commercial Growers. University of Massachusetts Cooperative Extension System. 36 p.

Gillespie, D.R. 1995? Development of integrated pest management and biological control systems for the production of greenhouse crops. http://res.agr.ca/agassiz/studies/gill95.htm (Link no longer active). 6 p.

Resources

Books

Applied Bio-nomics, Ltd. (ed). 1993. Biological Technical Manual. Applied Bio-nomics, Ltd., Sidney, B.C. 490 p.
A comprehensive text on the biology and use of beneficial insects and mites for biological control in greenhouses. The manual includes biology, life cycles, release instructions, pesticide compatibilities, and crop programs for greenhouse tomatoes, poinsettias, floricultural crops, and interior plantscapes. It has been in revision for several years and is unavailable for purchase. However, you might be able to obtain a copy through inter-library loan or at a used bookstore.

Hunter, Charles D. 1997. Suppliers of Beneficial Organisms in North America. PM 97-01. California Environmental Protection Agency, Department of Pesticide Regulation. Sacramento, CA. 32 p.
The booklet lists 143 commercial suppliers of more than 130 beneficial organisms used for biological control, including a special section on greenhouse biological control. The booklet can be downloaded from their Web site, or free, single copies can be obtained from:

Hussey, N.W. and N. Scopes (ed). 1985. Biological Pest Control: The Glasshouse Experience. Cornell University Press, Ithaca, NY. 240 p.
This book is a comprehensive work that explains the life cycles of both pests and biological control agents. All of the major and minor greenhouse pests are covered. This book is no longer in print, but you may be able to get it through inter-library loan or at a used bookstore.

Lindquist, Richard. 1998. Identification of Insects and Related Pests of Horticultural Plants. Ohio Florists' Assocation, Columbus, OH. 44 p.
Illustrates the life cycle and crop damage of ten major pests. The 20-page Appendix: Insect Cocktail provides information on combining chemical and biological tools for use against pests. Available for $27 from:

Malais, M. and W.J. Ravensburg. 1992. Knowing and Recognizing: The Biology of Glasshouse Pests and Their Natural Enemies. Koppert B.V., Berkel en Rodenrijs, Netherlands. 109 p.
This book includes photographs, drawings, and life cycle diagrams for both pests and beneficials of greenhouse crops. In the U.S., it is available for $50 through:

Jarvis, William. 1995. Managing Diseases in Greenhouse Crops. American Phytopathological Press, St. Paul, Minnesota. 228 p.
This is the definitive text on managing diseases in greenhouses. Included are useful sections on biological control and integrated disease management. The style is more akin to an academic book rather than a grower's manual, yet little else has been published on this topic. It lists for about $85 + $5 s&h.Contact:

Greenhouse Grower magazine publishes IPM manuals on the control of greenhouse whiteflies and thrips. The two publications, Win the War on Whiteflies, and Get a Grip on Thrips, are an assortment of selected articles published in the magazine over the span of several years. They are available for $12 each from Meister Publishing Company (see address above)

Periodicals

Bio-Integral Resource Center (BIRC) is a leader in the field of integrated pest management. BIRC publishes The IPM Practitioner and Common Sense Pest Quarterly. In addition, they publish a directory of IPM products and beneficial insects. BIRC also offers booklets and reprints on least-toxic controls for selected pests. For a copy of BIRC's catalog & list of services, contact:

Cornell and Rutgers Cooperative Extension publish Northeast Greenhouse IPM Notes, formerly titled Greenhouse IPM Update, a monthly newsletter designed to help growers incorporate IPM into their operations throughout the growing season. The newsletter reports on new products, publications, and current issues in greenhouse IPM, as well as providing the most up-to-date information on inidual pests and crops. The hard copy version costs $50 a year, but the newsletter is free over the Internet. Contact:

Midwest Biological Control NewsDept. of Entomology
University of Wisconsin
1630 Linden Dr.
Madison, WI 53706
608-262-9914
This newsletter is no longer being published, but all back issues are available online.

Video

Integrated Pest Management in Greenhouses. 27 minutes.
Shows the unique problems and opportunities involved with managing pests in production greenhouses. Covers economic thresholds and how to apply an IPM program to coordinate physical, biological, cultural, horticultural, and chemical controls. Comes with a 72-page book on greenhouse pest problems. Available for $95 from:

Conference

The Society of American Florists holds an annual Pest Management Conference in February. This is usually a three-day event that focuses on pest management in ornamental crops. Annual conference proceedings are available for $17.95. For more information, contact:

1-3/10 sq. ft.; humidity should be 50-90%, temp 60-80°F. Release when aphids are first observed; release lower numbers for preventive control; apply every two weeks. Active at night; sensitive to daylength.

Release 1/sq. ft. weekly for 3 weeks when pest numbers are low. Release 2-4/sq. ft. when pest numbers are high. apply when epsts are first observed. Should be used in conjunction with traps. May be used along with other beneficials. E. formosa is very susceptible to chemicals. Temps should be at least 64°F. Re-apply every two weeks.

Capable of handling hot, dry temperatures. Introduce when whiteflies are first observed. May be used in combination with other beneficials such as green lacewings. Eretmocerus is more tolerant of pesticides than Encarsia formosa.

1/10 sq. ft. (preventive), 1 every 2 sq. ft. when pests are present. Temperature should be 70-90°F. Orius are dormant September-April. Re-apply every 2-3 weeks. Very susceptible to pesticides. Works well in combination with Neoseiulus cucumeris.

Phytoseiulus longipes or Mesoseiulus longipes
(predator)

Arbico, Nature's Control, Harmony Farm Supply

spider mites

Introduce at first sign of pests. Can tolerate hot, dry conditions (humidity 40%, temp. 70-90°F). tolerates extremes of temp. and humidity better than other mite predators.

2000 mites/3000 sq. ft or 1/5 sq. ft. Apply at first sign of spider mites. If pests persist, re-apply every 3-5 weeks. Can be used in combination with either Galendromus occidentalis or Neoseiulus californicus. May be used in combination with Bt or Enstar II. Also available in P. persimilis Ht for higher temperatures. Humidity should be 60-90%, temps. 65-80°F.

Propylea quatuordecimpuncata
(predatory beetle)

Praxis

aphids

Rhizobius lophanthae or Lindorus lophanthae
(black lady beetle)

Harmony Farm Supply, Arbico, Green Spot

armored scales

1-2/sq. ft. Release as soon as scales are detected. Temps. should be 59-77°F, RH of 20-90%